Raphaël Glucksmann, the top candidate for the Socialists in the European elections, was forced to leave a May Day protest after he was targetted by a group of far-left activists. He pointed the blame at the leader of the radical left Jean-Luc Mélenchon.
Unions had called for a major strike on Thursday after a breakdown of negotiations on salary increases and other measures in a planned overhaul of France's air traffic control system.
Five months after the elections, the Dutch right and far right are still unable to form a government. The Socialist-Green coalition, which came second in the elections, could take over as early as this week.